A conventional optical fiber cable product may comprise a plurality of optical fibers supported in a fiber optic cable component, for example, a spacer body. The spacer body is formed of a thermoplastic material and is provided with a structural surface. The surface may comprise a plurality of recesses. The recesses are adapted to receive and retain optical fibers therein. The recesses must conform to product specifications so that the fibers will not be over-stressed. Undue bending stresses, induced in the fibers from recesses which do not conform to specifications, may negatively affect the ability of the fibers to transmit signals. Additionally, the spacer body should be of specified tensile and crush strengths, and comprise a suitable number of recesses. The spacer body may comprise a central member, for example, a member for imparting strength and/or anti-buckling to the fiber optic cable product. Where the spacer body includes such a strength member, product specifications may require that the ratio of the diameter of the strength member to the root diameter is maintained. The root diameter is the minimum diametrical distance between the respective bottoms of opposing recesses.
A conventional spacer body is made by extruding a hot, molten thermoplastic material. A tool, termed an extrusion die, is used in the extrusion process. The die can be stationary or rotary, but will comprise a die opening through which the thermoplastic material is extruded under pressure. The opening will form the shape of the outer surface of the thermoplastic material during extrusion. As the spacer body cools, the thermoplastic material hardens into an essentially final shape. The final shape should conform to a set of product specifications.
However, formation of the spacer body surface according to desired product specifications may be difficult. A substantially deformed spacer body profile will not meet product specifications. A primary contributor to distortion is gravity, which may distort the soft mass of material after the extrusion process but before cooling of the spacer body especially in the case of spacer bodies of large cross-section. Such deformation is termed slumping.
Conventional methods for forming fiber optic cable components are relatively expensive. U.S. Pat. No. 4,814,133 relates to a method of forming the spacer of an optical fiber cable. The spacer includes a strength member, which is covered by a spacer body of thermoplastic material. The spacer body is made up of an intermediate layer which surrounds the strength member, and an outer layer which surrounds the intermediate layer. The two-layer design adds to manufacturing costs. U.S. Pat. No. 4,781,434 describes a method for forming the spacer of an optical fiber cable including the steps of providing a strength member and covering it with a spacer body. The process of manufacture is costly because a technique-sensitive die is used to maintain close tolerances. The foregoing methods are disadvantageous in that they are not cost efficient and may produce fiber optic cable components which are subject to a high degree of slumping.